If your goals is to make 500whp reliably youre gonna need way more then 20k. Also if you want to make power stay away from the MR's the 6 speed trans are weak. As far as the 5 speed and the diff's they are all strong except for the 03's but either way getting the tranny and transfer case isnt too expensive. You can deff find a nice evo for a little under 20k but you will probably need another 20k to make 500whp reliably.